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            Composite</title>
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<h1>Class Composite</h1>
<div class="classSig">public 
            class 
            Composite<br>extends
                <a xmlns="" href="com.google.gwt.user.client.ui.Widget.html">Widget</a>
<br>
<br>// Superclass of <code><a href="com.google.gwt.user.client.ui.TabBar.html">TabBar</a></code>, <code><a href="com.google.gwt.user.client.ui.TabPanel.html">TabPanel</a></code>
</div>A type of widget that can wrap another widget, hiding the wrapped widget's
 methods. When added to a panel, a composite behaves exactly as if the widget
 it wraps had been added.
 
 <p>
 The composite is useful for creating a single widget out of an aggregate of
 multiple other widgets contained in a single panel.
 </p>
<p>
<h3>Example</h3>
<pre class="code">public class CompositeExample implements EntryPoint {

  /**
   * A composite of a TextBox and a CheckBox that optionally enables it.
   */
  private static class OptionalTextBox extends Composite implements
      ClickListener {

    private TextBox textBox = new TextBox();
    private CheckBox checkBox = new CheckBox();

    /**
     * Constructs an OptionalTextBox with the given caption on the check.
     * 
     * @param caption the caption to be displayed with the check box
     */
    public OptionalTextBox(String caption) {
      // Place the check above the text box using a vertical panel.
      VerticalPanel panel = new VerticalPanel();
      panel.add(checkBox);
      panel.add(textBox);

      // Set the check box's caption, and check it by default.
      checkBox.setText(caption);
      checkBox.setChecked(true);
      checkBox.addClickListener(this);

      // All composites must call setWidget() in their constructors.
      initWidget(panel);

      // Give the overall composite a style name.
      setStyleName("example-OptionalCheckBox");
    }

    public void onClick(Widget sender) {
      if (sender == checkBox) {
        // When the check box is clicked, update the text box's enabled state.
        textBox.setEnabled(checkBox.isChecked());
      }
    }

    /**
     * Sets the caption associated with the check box.
     * 
     * @param caption the check box's caption
     */
    public void setCaption(String caption) {
      // Note how we use the use composition of the contained widgets to provide
      // only the methods that we want to.
      checkBox.setText(caption);
    }

    /**
     * Gets the caption associated with the check box.
     * 
     * @return the check box's caption
     */
    public String getCaption() {
      return checkBox.getText();
    }
  }

  public void onModuleLoad() {
    // Create an optional text box and add it to the root panel.
    OptionalTextBox otb = new OptionalTextBox("Check this to enable me");
    RootPanel.get().add(otb);
  }
}
</pre>
</p>
<h2 class="api">Methods</h2>
<table cellpadding="1" cellspacing="1" class="members">
<tr>
<td><a href="com.google.gwt.user.client.ui.Composite.html#getElement()">getElement()</a></td><td>This override checks to ensure <a href="com.google.gwt.user.client.ui.Composite.html#initWidget(com.google.gwt.user.client.ui.Widget)">initWidget(Widget)</a> has been called. </td>
</tr>
<tr>
<td><a href="com.google.gwt.user.client.ui.Composite.html#initWidget(com.google.gwt.user.client.ui.Widget)">initWidget(Widget)</a></td><td>Sets the widget to be wrapped by the composite. </td>
</tr>
<tr>
<td><a href="com.google.gwt.user.client.ui.Composite.html#onAttach()">onAttach()</a></td><td>This method is called when a widget is attached to the browser's document. </td>
</tr>
<tr>
<td><a href="com.google.gwt.user.client.ui.Composite.html#onDetach()">onDetach()</a></td><td>This method is called when a widget is detached from the browser's
 document. </td>
</tr>
<tr>
<td><a href="com.google.gwt.user.client.ui.Composite.html#setWidget(com.google.gwt.user.client.ui.Widget)">setWidget(Widget)</a></td><td>Sets the widget to be wrapped by the composite. </td>
</tr>
</table>
<h2 class="api">Method Detail</h2>
<a name="getElement()"></a>
<h3 class="api">getElement</h3>
<div class="memberSig">public <a href="com.google.gwt.user.client.Element.html">Element</a><b> getElement</b>()</div>This override checks to ensure <a href="com.google.gwt.user.client.ui.Composite.html#initWidget(com.google.gwt.user.client.ui.Widget)">initWidget(Widget)</a> has been called.<hr>
<a name="initWidget(com.google.gwt.user.client.ui.Widget)"></a>
<h3 class="api">initWidget</h3>
<div class="memberSig">protected void<b> initWidget</b>(<nobr><a href="com.google.gwt.user.client.ui.Widget.html">Widget</a> widget</nobr>)</div>Sets the widget to be wrapped by the composite. The wrapped widget must be
 set before calling any <a href="com.google.gwt.user.client.ui.Widget.html">Widget</a> methods on this object, or adding it
 to a panel. This method may only be called once for a given composite.<h4 class="api">Parameters</h4>
<dl class="memberDetail">
<dt>widget</dt>
<dd>the widget to be wrapped</dd>
</dl>
<hr>
<a name="onAttach()"></a>
<h3 class="api">onAttach</h3>
<div class="memberSig">protected void<b> onAttach</b>()</div>This method is called when a widget is attached to the browser's document.
 It must not be overridden, except by <a href="com.google.gwt.user.client.ui.Panel.html">Panel</a>. To receive
 notification when a widget is attached to the document, override the
 <a href="com.google.gwt.user.client.ui.Widget.html#onLoad()">onLoad</a> method.<hr>
<a name="onDetach()"></a>
<h3 class="api">onDetach</h3>
<div class="memberSig">protected void<b> onDetach</b>()</div>This method is called when a widget is detached from the browser's
 document. It must not be overridden, except by <a href="com.google.gwt.user.client.ui.Panel.html">Panel</a>.<hr>
<a name="setWidget(com.google.gwt.user.client.ui.Widget)"></a>
<h3 class="api">setWidget</h3>
<div class="memberSig">protected void<b> setWidget</b>(<nobr><a href="com.google.gwt.user.client.ui.Widget.html">Widget</a> widget</nobr>)</div>Sets the widget to be wrapped by the composite.<h4 class="api">Parameters</h4>
<dl class="memberDetail">
<dt>widget</dt>
<dd>the widget to be wrapped</dd>
</dl>
</div>
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